Anti- and pro-oxidant factors and endothelial dysfunction in chronic cigarette smokers with coronary heart disease.

BACKGROUND: Endothelial dysfunction in cigarette smokers has been ascribed to increased oxidative damage. The aims of the present study were to compare the endothelial function of normotensive smokers with that of non-smokers and to examine its relation to some parameters representative of oxidative damage and of antioxidant capacity. METHODS: We investigated 32 chronic smokers (15-30 cigarettes daily) affected by coronary heart disease, ranging from acute myocardial infarction to instable angina pectoris, and 28 matched non-smokers without any definite risk factors. All subjects underwent assessment of nitric oxide (NO)-dependent endothelial function, measured as brachial artery vasodilatation in response to reactive ischemia, using a standardized echographic method. Plasma and urinary levels of NO were also measured in all subjects, as were urinary 15-isoprostane F(2t), plasma serum lipids, homocysteine (Hcy), ascorbic acid, retinol, tocopherol, and alpha- and beta-carotene (by high-performance liquid chromatography). RESULTS: Smokers showed a significantly lower NO-mediated vasodilatation response (3.50% vs. 6.18%, p<0.001) and higher levels of urinary NO metabolites and 15-isoprostane F(2t). They also had higher levels of Hcy (p<0.001); these values were significantly and inversely related to NO serum levels (r=-0.512, p<0.001). Moreover, smokers had a significant and corresponding reduction in circulating levels of ascorbic acid, tocopherol, and alpha- and beta-carotene. CONCLUSIONS: The present study shows a clear relation between endothelial dysfunction (NO production impairment) and cigarette smoking, especially in the presence of high levels of LDL-cholesterol. It also defines some markers of both oxidative damage and antioxidant protective capacity in this condition. The monitoring of these factors may be advisable in order to assess the amount of endothelial damage.

Pro-oxidant and antioxidant factors in acute intermittent porphyria: family studies.

Given the crucial role of iron and porphyrins in oxidative cellular damage in the chronic porphyrias, we undertook an extensive study in families with acute porphyrias to evaluate the possible role of similar oxidative damage in these diseases, whose natural history is often also complicated by neoplastic evolution. Four unrelated patients with acute intermittent porphyria (AIP) were studied together with 37 members of four different families. Aminolevulinic acid and porphobilinogen were measured in urine, and porphyrins in urine, plasma and stools. The activity of the congenitally deficient enzyme, porphobilinogen deaminase, and the concentrations of plasma iron, transferrin, ferritin, and various antioxidants (ascorbic acid, retinol, tocopherol, alpha- and beta-carotene, by a personal HPLC method) and the urinary and plasma metabolites of nitrous oxide were also assayed. The results showed no relationship between the observed increase of porphyrin metabolites and the presence of markers of oxidative damage or the decrease of circulating antioxidants: however, when such a decrease was registered, it depended on spontaneous or iatrogenic iron accumulation. We conclude that family screening, recommended for the identification of AIP carriers, must also include evaluation of iron stores with a view to preventing the oxidative damage and in order to forestall the neoplastic evolution of the disease.

Antioxidant liposoluble vitamins and carotenoids in chronic hepatitis.

Background: It is known that antioxidant liposoluble vitamins and carotenoids are reduced in liver cirrhosis, but little is known about chronic viral hepatitis, where oxidative damage has to be taken into account. Methods: Fifty-five patients with chronic hepatitis, mainly C virus-related, were matched with 16 patients with biliary stones and 20 healthy controls. Plasma and liver analyses were carried out using a well-tried HPLC technique that affords an accurate quantification of retinol, tocopherol, alpha- and beta-carotene, cryptoxanthin, and lycopene. Results: Plasma concentration of retinol, tocopherol, beta-carotene, and lycopene was significantly decreased in both patient groups, particularly in those with chronic hepatitis. In contrast, liver concentration of both esterified and free retinol, tocopherol, and some carotenoids was better preserved in the hepatitis group than in the cholelithiasis group. A strict correspondence between aminotransferases and the amount of liver-stored retinol was documented. Conclusions: Plasma vitamin and carotenoid depletion co-existing with preserved liver storage may indicate a functional defect in liver pool mobilization or even a real depletion of the antioxidant defenses, which play a key role in averting cellular damage. The implications for nutrition and therapy need to be taken into account.

Circulating pro- and antioxidant factors in iron and porphyrin metabolism disorders.

BACKGROUND: Porphyria cutanea tarda and haemochromatosis are taken to be spontaneous human models of oxidative cellular damage, with an increased risk of fibrosis and cancer evolution. AIM: To define the relative pro-oxidant roles of porphyrin and iron, in their different molecular forms, and their effects on antioxidant biological systems. PATIENTS: A group of 17 patients with porphyria cutanea tarda and a group of 14 patients with primary and secondary haemochromatosis, were compared with 21 healthy controls. METHODS: Plasma retinol, tocopherol, alpha- and beta-carotene, ascorbic acid, glutathione, malonyldialdehyde and red blood cell free iron were determined using high performance liquid chromatography. RESULTS: Only a modest increase in iron stores was demonstrated in the porphyria cutanea tarda group; in the haemochromatosis patients ferritin levels were almost seven times higher. By contrast, there was a sharp and virtually identical increase in red blood cell free iron and malonyldialdehyde in both the patient groups. A significant reduction was observed in retinol, alpha-, beta-carotene and red blood cell glutathione levels being more marked in porphyria cutanea tarda than in haemochromatosis patients. CONCLUSIONS: The study confirms the strong pro-oxidant effects of porphyrins in vivo, through an induction of the free toxic iron form, even though the total iron pool is not greatly expanded. The additional free-iron and porphyrin oxidant effects are documented both in red blood cell and plasma in the porphyria cutanea tarda group. It confirmed that aging exerts a negative influence in terms of pro- and antioxidant balance in all cases, but particularly in the haemochromatosis group.

Hepatic tocopherol content in primary hepatocellular carcinoma and liver metastases.

The high incidence of hepatocellular carcinoma (HCC) in cirrhosis, where previous studies have indicated a severe reduction in several antioxidant vitamin factors, prompted us to compare plasma liposoluble vitamins with tocopherol content in healthy and neoplastic liver tissue in humans. This, with a view to a more positive preventive dietary approach, given the conflicting results obtained by liposoluble vitamin dietary supplementation in different malignancies. Eleven patients with cirrhosis, 18 patients affected by cirrhosis with HCC, and 10 patients with liver metastases (LM) from digestive tract adenocarcinomas were compared with controls who had undergone perlaparoscopic cholecistectomy. Plasma alpha- and beta-carotene, retinol and tocopherol, together with liver tocopherol, from both nonmalignant portions and malignant nodules of the same organ, were determined by high-performance liquid chromatography following a well-assessed technique. The results confirm a trend towards a reduction in circulating carotenoids and tocopherol in cirrhosis and in patients affected by cirrhosis with HCC. Tocopherol content in liver tissue is significantly decreased in cirrhosis (0.26 + 0.03 micromol/g prot., mean + SEM, P < .001) and in cirrhotic areas of the HCC group (0.31 + 0.02, P < .002), with respect to its content in liver specimens of healthy controls (0.46 + 0.03) and in healthy areas of the same organ in patients with LM (0.41 + 0.03). Tocopherol concentration is further reduced by 50% in malignant liver nodules of HCC, with respect to surrounding cirrhotic tissue, whereas in metastatic liver nodules from digestive neoplasms the tocopherol content is almost twice that of healthy surrounding areas. This unpredictable tocopherol behavior in liver specimens, of secondary as opposed to primary malignancies of the liver, affords further insight into the conflicting effects of liposoluble vitamins employed in the chemopreventive treatment of different malignant diseases, where hepatic tocopherol concentration show opposite trends: halved in primary HCC and doubled in LM of digestive adenocarcinomas, with respect to healthy controls.

Antioxidant activity of silybin in vivo during long-term iron overload in rats.

BACKGROUND & AIMS: Hepatic iron toxicity may be mediated by free radical species and lipid peroxidation of biological membranes. The antioxidant property of silybin, a main constituent of natural flavonoids, was investigated in vivo during experimental iron overload. METHODS: Rats were fed a 2.5% carbonyl-iron diet and 100 mg.kg body wt-1.day-1 silybin for 4 months and were assayed for accumulation of hepatic lipid peroxidation by-products by immunocytochemistry, mitochondrial energy-dependent functions, and mitochondrial malondialdehyde content. RESULTS: Iron overload caused a dramatic accumulation of malondialdehyde-protein adducts into iron-filled periportal hepatocytes that was decreased appreciably by silybin treatment. The same beneficial effect of silybin was found on the iron-induced accumulation of malondialdehyde in mitochondria. As to the liver functional efficiency, mitochondrial energy wasting and tissue adenosine triphosphate depletion induced by iron overload were successfully counteracted by silybin. CONCLUSIONS: Oral administration of silybin protects against iron-induced hepatic toxicity in vivo. This effect seems to be caused by the prominent antioxidant activity of this compound.

Vitaminas liposolubles y carotenoides naturales en pacientes porfiricos / Liposolubles vitamins and naturally carotenoids in porphyric patients

Se ha llevado a cabo un estudio comparativo de los niveles de las vitaminasliposolubles y carotenoides naturales y las porfirinas plasmáticas en pacientes porfiricos y controles, completado con la determinación de otros parámetros bioquímicos que caracterizan la patología, con el objeto de evaluar el deterioro del sistema antioxidante liposoluble en las porfirias cutáneas y no cutáneas. Se recogieron muestras de sangre y orina de 68 pacientes porfíricos, 20 con porfiria cutánea tardia (PCT) sintomática, 15 con protoporfiria eritropoyética manifiesta, 15 con porfiria variegata (PV) en remisión,18 con porfiria aguda intermitente (PAI) latente. Se midió el contenido de retinol,tocoferol,alfa y beta carotenos, criptoxantina, zeoxantina y licopeno,índice de porfirinas plasmáticas (IPP),porfirinas totales (PTS) y la actividad de deaminasa en sangre,de aminolevúlico (ALA), porfobilinógeno (PBG)y porfirinas en orina. El IPP estuvo elevado en PCT=4,5 mas menos 1,1 (lambda=625 nm),enEPP= 2,53 mas menos 0,5 (lambda = 635 nm), en PV=4,3 mas menos 0,5 (lambda= 625nm) y normal(menor o igual 1,3 ,lambda = 618 nm) en PAI.El contenido de retinol estuvo dentro de los valores normales en todos los grupos (63,8-102,3 ug/dl). El tocoferol se encontró disminuido en PCT (970 mas menos12 ug/dl y PPe (668 mas menos 10 ug/dl) y dentro de los valores normales(1040 mas menos 1260 ug/dl) en PAI y PV, mientras quezeoxantina estuvo solo disminuída en PCT=18 mas menos 2 ug/dl y PPE =10,3 mas menos 1,3 ug/dl y normal (40,5 mas menos 1,3 ug/dl) en PAI y PV. Los valores de los carotenoides criptoxantina y licopeno fueron para PAI= 11,1 mas menos 2,1 ug/dl y 13,2 mas menos 2,1 ug/dl,PV=10,3 mas menos 1,1 ug/dl y 2,1 mas menos 0,9 ug/dl,PCT=9,1 mas menos 1,2 ug/dl y 9,2 mas menos 0,9 ug/dl y PPE= 11,3 mas menos 1,3 ug/dl y8,3 mas menos 1,1 ug/dl, menores que los respectivos valores normales 37,9 mas menos 1,2 ug/dl y 19,5 mas menos 0,9 ug/dl. Alfa y beta carotenos estuvieron reducidos en PV=1,0 mas menos 1,2 ug/dl y 4,8 mas menos 0,8 ug/dl, en PCT= 1,2 mas menos 0,6 ug/dl y 4,0 mas menos 0,8 ug/dl y PPE =2,5 mas menos 1,0 ug/dl y 8,5 mas menos 1,0 ug/dl( valores normales = 1,9 mas menos 0,3 ug/dl y 9,3 mas menos 0,5 ug/dl). Para el grupo de Pai sólo estuvo disminuido el contenido de beta carotenos ( 6,1 mas menos 1,2 ug/dl. Estos resultados muestran que el sistema liposoluble antioxidante tiene una capacidad reducida en pacientes porfíricos(AU)

Vitaminas liposolubles y carotenoides naturales en pacientes porfiricos / Liposolubles vitamins and naturally carotenoids in porphyric patients

Se ha llevado a cabo un estudio comparativo de los niveles de las vitaminasliposolubles y carotenoides naturales y las porfirinas plasmáticas en pacientes porfiricos y controles, completado con la determinación de otros parámetros bioquímicos que caracterizan la patología, con el objeto de evaluar el deterioro del sistema antioxidante liposoluble en las porfirias cutáneas y no cutáneas. Se recogieron muestras de sangre y orina de 68 pacientes porfíricos, 20 con porfiria cutánea tardia (PCT) sintomática, 15 con protoporfiria eritropoyética manifiesta, 15 con porfiria variegata (PV) en remisión,18 con porfiria aguda intermitente (PAI) latente. Se midió el contenido de retinol,tocoferol,alfa y beta carotenos, criptoxantina, zeoxantina y licopeno,índice de porfirinas plasmáticas (IPP),porfirinas totales (PTS) y la actividad de deaminasa en sangre,de aminolevúlico (ALA), porfobilinógeno (PBG)y porfirinas en orina. El IPP estuvo elevado en PCT=4,5 mas menos 1,1 (lambda=625 nm),enEPP= 2,53 mas menos 0,5 (lambda = 635 nm), en PV=4,3 mas menos 0,5 (lambda= 625nm) y normal(menor o igual 1,3 ,lambda = 618 nm) en PAI.El contenido de retinol estuvo dentro de los valores normales en todos los grupos (63,8-102,3 ug/dl). El tocoferol se encontró disminuido en PCT (970 mas menos12 ug/dl y PPe (668 mas menos 10 ug/dl) y dentro de los valores normales(1040 mas menos 1260 ug/dl) en PAI y PV, mientras quezeoxantina estuvo solo disminuída en PCT=18 mas menos 2 ug/dl y PPE =10,3 mas menos 1,3 ug/dl y normal (40,5 mas menos 1,3 ug/dl) en PAI y PV. Los valores de los carotenoides criptoxantina y licopeno fueron para PAI= 11,1 mas menos 2,1 ug/dl y 13,2 mas menos 2,1 ug/dl,PV=10,3 mas menos 1,1 ug/dl y 2,1 mas menos 0,9 ug/dl,PCT=9,1 mas menos 1,2 ug/dl y 9,2 mas menos 0,9 ug/dl y PPE= 11,3 mas menos 1,3 ug/dl y8,3 mas menos 1,1 ug/dl, menores que los respectivos valores normales 37,9 mas menos 1,2 ug/dl y 19,5 mas menos 0,9 ug/dl. Alfa y beta carotenos estuvieron reducidos en PV=1,0 mas menos 1,2 ug/dl y 4,8 mas menos 0,8 ug/dl, en PCT= 1,2 mas menos 0,6 ug/dl y 4,0 mas menos 0,8 ug/dl y PPE =2,5 mas menos 1,0 ug/dl y 8,5 mas menos 1,0 ug/dl( valores normales = 1,9 mas menos 0,3 ug/dl y 9,3 mas menos 0,5 ug/dl). Para el grupo de Pai sólo estuvo disminuido el contenido de beta carotenos ( 6,1 mas menos 1,2 ug/dl. Estos resultados muestran que el sistema liposoluble antioxidante tiene una capacidad reducida en pacientes porfíricos

Liposoluble vitamins and naturally occurring carotenoids in porphyria cutanea tarda.

The authors consider two groups of patients with overt sporadic porphyria cutanea tarda (PCT) from different continents, with the aim of evaluating the possible impairment of the liposoluble antioxidative system, given the possible synergic effect of porphyrins and iron in promoting oxidative cellular damage. Twenty-three Italian outpatients with overt sporadic PCT and 11 outpatients with PCT from Buenos Aires (Argentina) were matched with 60 patients with liver cirrhosis and 52 healthy Italian controls. Serum levels of alpha- and beta-carotene, cryptoxanthin, zeaxanthin, lutein, lycopene, retinol and alpha-tocopherol were detected by a high-performance liquid chromatographic technique devised in our laboratory, which afforded an accurate and simultaneous resolution of all these compounds. The results point to a significant reduction in plasma levels of alpha- and beta-carotene in both the PCT populations with respect not only to controls, but also to the cirrhotic population, which had more severe liver damage. Moreover, other carotenoids with proven antioxidative properties, like cryptoxanthin and lycopene, are greatly reduced in our PCT populations. This confirms the suggested synergic effect of iron and porphyrins in the oxidative intracellular damage with consequent depletion of antioxidative liposoluble molecules.

Molecular and cellular aspects of iron-induced hepatic cirrhosis in rodents.

Hepatic fibrosis and cirrhosis are common findings in humans with hemochromatosis. In this study we investigated the molecular pathways of iron-induced hepatic fibrosis and evaluated the anti-fibrogenic effect of vitamin E. Male gerbils were treated with iron-dextran and fed a standard diet or a alpha-tocopherol enriched diet (250 mg/Kg diet). In gerbils on the standard diet at 6 wk after dosing with iron, in situ hybridization analysis documented a dramatic increase of signal for collagen mRNA around iron foci onto liver fat storing cells (FSC), as identified by immunocytochemistry with desmin antibody. After 4 mo, micronodular cirrhosis developed in these animals, with nonparenchymal cells surrounding hepatocyte nodules and expressing high level of TGF beta mRNA. In this group, in vivo labeling with [3H]-thymidine showed a marked proliferation of nonparenchymal cells, including FSC. In iron-dosed gerbils on the vitamin E-enriched diet for 4 mo, in spite of a severe liver iron burden, a normal lobular architecture was found, with a dramatic decrease of collagen mRNA accumulation and collagen deposition. At the molecular level, a total suppression of nonparenchymal cell proliferation was appreciable, although expression of collagen and TGF beta mRNAs was still present into microscopic iron-filled nonparenchymal cell aggregates scattered throughout the hepatic lobule. In conclusion, our study shows that anti-oxidant treatment during experimental hepatic fibrosis arrests fibrogenesis and completely prevents iron induced hepatic cirrhosis mainly through inhibition of nonparenchymal cell proliferation induced by iron.

Duodenal ferritin synthesis in genetic hemochromatosis.

BACKGROUND/AIMS: The molecular defect of genetic hemochromatosis (GH) is unknown. It is believed that low expression of duodenal ferritin in GH is caused by tissue or cell specific defect of ferritin synthesis. Our study was designed to ascertain whether the control of duodenal ferritin synthesis in GH was defective. METHODS: Expression at the single cell level of H and L ferritin messenger RNAs and protein and activity of the iron regulatory factor, which controls the translation of ferritin messenger RNA, were assessed in 43 duodenal biopsy specimens from individuals with GH, secondary hemochromatosis (SH), anemia, or normal iron balance. RESULTS: Signal for ferritin H and L subunit messenger RNAs was detected in both absorptive and nonabsorptive cells by in situ hybridization, but in 10 of 14 patients with untreated GH, the signal was lower than in patients with SH or normal subjects. However, immunostaining for ferritin protein documented a diffuse/cytoplasmic pattern, whereas a supranuclear/granular staining was found in normal subjects or patients with SH. The spontaneous activity of duodenal iron regulatory factor was consistently higher in patients with GH than in normal subjects or subjects with anemia or SH. CONCLUSIONS: In patients with GH, ferritin gene transcription is preserved in both absorptive and nonabsorptive intestinal cells. Low accumulation of ferritin is not caused by a defective control of ferritin synthesis but by low expression of ferritin messenger RNA and sustained activity of iron regulatory factor.

Excess iron into hepatocytes is required for activation of collagen type I gene during experimental siderosis.

BACKGROUND/AIMS: Liver fibrosis and cirrhosis represent common pathological findings in humans with iron overload. This study was undertaken to assess whether in vivo targeting of iron to liver parenchymal or nonparenchymal cells would differently affect collagen gene activity. METHODS: Rats were treated with an iron diet or intramuscular injections of iron dextran, and in situ hybridization analyses on liver samples were performed. RESULTS: These iron treatments determined parenchymal or reticuloendothelial cell iron overload, respectively. The typical distribution of iron into different liver cells was documented by histochemistry and confirmed by in situ hybridization analysis with a ferritin L complementary RNA probe. In iron-fed rats, in situ hybridization analysis identified a signal for collagen type I messenger RNA into nonparenchymal cells in zones I and II. In rats with nonparenchymal cell iron overload, no activation of collagen gene expression was detected into or near iron-laden nonparenchymal cells. These findings were also confirmed by quantitative Northern blot analysis. CONCLUSIONS: The results of this study indicate that, regardless of the total hepatic iron burden, selective localization of iron into liver cells (i.e., parenchymal cells) is required for the activation of collagen gene during long-term iron overload in rodents.

Zinc and magnesium in liver cirrhosis.

The Authors determined zinc (Zn) and magnesium (Mg) in the plasma, urine, erythrocytes (RBCs), mono- and polymorphonuclear cells (MNCs and PMNs) of patients with overt alcoholic and non-alcoholic liver cirrhosis. In order to obtain a clearer clinical picture, biochemical and nutritional parameters (retinol, tocopherol, six different carotenoids, creatinine-height index and tricipital skinfold), as well as markers of portal hypertension (spleno-portal size and platelet count) were also evaluated. The plasma levels of Zn and Mg were found to be reduced, as were the urine levels of Mg. Urine Zn, on the other hand, was higher than normal. Plasma Zn correlated inversely, and urine Zn directly, with the severity of the disease, rather than with alcohol consumption or treatment with diuretics. Protein metabolism impairment would appear to affect the plasma transport of Zn rather than its overall availability in the organism; the opposite was found in the case of Mg, the availability of which appeared to be reduced. Determination of the two elements in RBCs, MNCs and PMNs suggested that a true nutritional deficit cannot be demonstrated. MNCs, rather than RBCs or PMNs seem better to reflect tissue status of trace elements.

Enhanced hepatic collagen type I mRNA expression into fat-storing cells in a rodent model of hemochromatosis.

In recent years, identifying the hepatic cell type responsible for collagen synthesis in experimental models of postnecrotic or inflammatory fibrosis has been the subject of active investigation. In primary iron overload states, however, hepatic fibrosis and cirrhosis occur without accompanying necroinflammatory phenomena. In this study, we combined morphological, immunological, cell isolation and purification and molecular biological techniques to identify the hepatic cell responsible for enhanced collagen type I gene expression during chronic enteral iron overload in the rat. Ultrastructural analysis of liver tissue sections from iron-loaded rats specifically revealed an altered appearance of fat-storing cells, which showed few if any fat droplets left and increased rough endoplasmic reticulum. In situ hybridization analysis with specific complementary RNA probes identified enhanced signal for collagen type I into nonparenchymal cells in zones 1 and 2, without signal over the background onto iron-laden hepatocytes. Immunocytochemistry with desmin antibodies combined with in situ hybridization on the same tissue sections identified the cells expressing high level of collagen type I transcripts as fat-storing cells. Northern-blot analysis on RNA extracted from various purified cell isolates, confirmed the presence of collagen type I mRNA signal only into the fat-storing cells isolate. Our study shows that in an experimental model of metabolic fibrosis in which the hepatotoxin selectively accumulates into parenchymal cells, fat-storing cells are the main source of enhanced collagen type I gene expression.

Magnetic resonance imaging and different levels of iron overload in chronic liver disease.

The need for accurate and noninvasive evaluation of liver iron stores prompted us to evaluate the reliability of high-field magnetic resonance imaging equipment in liver patients with low or moderate siderosis, given the poor results obtained using systems operating at low field strength in such cases. Twenty patients with sporadic porphyria cutanea tarda and 28 with comparable chronic liver diseases (chronic hepatitis or cirrhosis) and moderate siderosis were compared with 10 patients with idiopathic or secondary hemochromatosis and 10 healthy controls. Plasma iron profile, ferritin concentration and liver iron concentration, determined with atomic absorption spectroscopy, were matched with the magnetic resonance parameters-namely, transverse relaxation time and the signal intensity for a given proton amount, obtained with equipment operating at a field strength of 1.5 T. Hemochromatosis patients with mean liver iron concentrations of 550 mumol/gm dry wt (vs. 10 mumol of controls) exhibited an impressive reduction in the signal intensity with respect to the other three groups, and this reduction prevented any further comparison with the same porphyria cutanea tarda and chronic liver disease groups, whose liver iron level was twice that of the controls. The signal intensity remained almost unchanged in the latter groups, whereas the transverse relaxation time was significantly reduced. Moreover, correlation with liver iron was significantly inverse in the case of the transverse relaxation time (n = 17, r = 0.62, p = 0.008) and direct in the case of the transverse relaxation rate. The transverse relaxation time values returned to normal in five patients who had completed an iron-depletion program.(ABSTRACT TRUNCATED AT 250 WORDS)

[The clinical implications of the use of an amino acid mixture without tryptophan in liver cirrhosis]. / Implicazioni cliniche dell' utilizzo di una miscela aminoacidica priva di triptofano nella cirrosi epatica.

The ingestion of an amino acid mixture lacking tryptophan causes a rapid fall of plasma tryptophan in healthy subjects. This is because amino acids elicit protein synthesis and endogenous tryptophan is incorporated into new proteins. If protein synthesis is the mechanism through which tryptophan-free solution decrease blood tryptophan, it may be interesting to study tryptophan levels after a tryptophan-free mixture in subjects with impaired protein synthesis. In the present paper we show that in 27 cirrhotics the administration of a tryptophan-free solution caused a fall of total plasma tryptophan that began significantly later than in 14 control subjects, the delay being significantly proportional to the severity of the disease. The difference between control and cirrhotic subjects was due to the bound fraction of plasma tryptophan. The diagnostic and clinical usefulness of our findings are discussed.

Regulation of transferrin, transferrin receptor, and ferritin genes in human duodenum.

To gain insights at the molecular level into the expression of iron-regulated genes [transferrin (Tf), transferrin receptor (TfR), and ferritin H and L subunits] in human intestinal areas relevant to iron absorption, the steady-state levels of specific messenger RNAs (mRNAs) were analyzed in gastric and duodenal samples obtained from 6 normal subjects, or 10 patients with anemia, 14 patients with untreated iron overload, and 8 patients with various gastrointestinal disorders. No Tf mRNA was detected in human gastroduodenal tissue, confirming earlier findings in the rat. In normal subjects, although higher levels of ferritin H- and L-subunit mRNAs were consistently found in duodenal than in gastric samples, no differences in the content of TfR transcripts were detected. However, a dramatic increase in TfR mRNA levels was specifically found in duodenal samples from subjects with mild iron deficiency but severe anemia. This response of the TfR gene is presumably secondary to decreased cellular iron content due to its accelerated transfer into the bloodstream, as also indicated by the low levels of ferritin subunit mRNAs found in the same tissue samples, and is not linked to faster growth rate of mucosal cells because no changes in duodenal expression of histone, a growth-related gene, were detected. In patients with secondary iron overload, a down-regulation of duodenal TfR gene expression and a concomitant increase in ferritin mRNA content were documented. On the contrary, a lack of TfR gene down-regulation and an abnormally low accumulation of ferritin H- and L-subunit mRNAs were detected in the duodenums of subjects with idiopathic hemochromatosis. Whether these molecular abnormalities in idiopathic hemochromatosis are relevant to the metabolic defect(s) of the disease is presently unknown.

Carotenoids and liposoluble vitamins in liver cirrhosis.

The role played by carotenoids, retinol and tocopherol in quencing oxidative cellular damage and combatting tumor growth is well documented, but little is known about their activity in human liver cirrhosis (LC), where oxidative damage and tumoral complications are common-place. We investigated 59 patients with LC of different etiology on admission to hospital and compared them with 32 healthy controls, matched for age and sex. Nutritional (cutaneous skinfolds, creatinine-height index) and serum parameters were determined; of these, alpha- and beta-carotene, cryptoxanthin, lycopene, retinol and alpha-tocopherol were detected by an high-performance liquid chromatographic (HPLC) technique, devised in our laboratory, which afforded an accurate and simultaneous resolution of all six compounds. The results point to a significant reduction in almost all the vitamin factors in LC, as well as in total serum lipids. In consequence, the ratio tocopherol/total serum lipids remains almost unchanged: 2.45 +/- 0.08 (m +/- se) in controls and 2.34 +/- 0.16 in patients. The effects of age, sex, nutritional habits, alcohol, malnutrition and the severity of the disease were also evaluated in relation to the vitamin-factor levels. It is suggested that the reduced levels observed in LC patients are due to a number of factors including portal hypertension and lymphatic circulation impairment, and it is concluded that thorough screening and improved diet are beneficial in the follow-up of LC.

Decrease in plasma tryptophan after a tryptophan-free amino acid solution. A comparison between cirrhotic and control subjects.

In healthy subjects the administration of an amino acid mixture devoid of tryptophan causes a marked decrease of plasma tryptophan. This is because amino acid mixtures induce protein synthesis and tryptophan in blood is incorporated into newly synthesized proteins. We hypothesized that a tryptophan-free mixture could differently affect plasma tryptophan levels in subjects with an impaired protein synthesis such as chronic liver patients. We studied tryptophan levels after a tryptophan-free amino acid solution in controls and cirrhotics fasting 12 hours. Plasma total tryptophan fell to 91% of the initial level 60 minutes after the administration of the diet, to 71% after 120, and to 50% after 210' in controls. In cirrhotics the solution caused a decrease of plasma tryptophan that began significantly later than in controls, the delay being proportional to the severity of the disease. Cirrhotics were subdivided into two groups in accordance to the Pugh modification of the Child-Turcotte criteria. Total plasma tryptophan was 100% of base line levels after 60', 88% after 120', and 65% after 210' in less severe clinical condition; total plasma tryptophan was 102% of base line levels after 60', 98% after 120', and 75% after 210' in more severe clinical condition.